Automatic bonding apparatus with multiple bonding heads

ABSTRACT

In apparatus for automatically wiring circuit boards in a pointto-point operation, a continuous supply of insulated wire extends through an opening in the bonding tip. Circuit boards are positioned on a table, one circuit board beneath each of the heads. A digital controller positions the table so that the heads are aligned with solder pads on the circuit boards. A control system for each head responds to signals from the digital controller. Each control system automatically operates the heads to lower the head into contact with a solder pad, to selectively apply heat to the pad to reflow solder the portion of the wire in contact with the pad, and to raise the head to its normal position. The control system also operates electrical continuity checks to determine if each bond has been properly made and to continuously monitor for stripped insulation on the wire which might cause short circuits. After each bond is made, the wire is mechanically stressed to insure that the bond has the required mechanical strength.

United States Patent [191 7' Steranko et al. Oct. 8, 1974 [54] AUTOMATIC BONDING APPARATUS WITH 3,392,256 7/1968 Bradharn, llt .......29/2 03 0 MULTIPLE BONDING HEADS P R b D B Id [75] Inventors: James Joseph Steranko, Weston; g gz gf gg i g g g Holland Frammgham Attorney, Agent, or Firm-Woodcock, Washburn,

0t 0 Kurtz & Mackiewicz [73] Assignee: Inforex, Inc., Burlington, Mass. by

said Holland [57] ABSTRACT [22] Filed; AP 2, 1973 In apparatus for automatically wiring circuit boards in a oint-tooint o eration, a continuous supply of in- P P P PP 353,465 sulated wire extends through an opening in the bond- Related A r D t ing tip. Circuit boards are positioned on a table, one [63] Continuatio of Se E 122 27 197 l circuit board beneath each of the heads. A digital conabandoned troller positions the table so that the heads are aligned with solder pads on the circuit boards. A control sys- [52] us Cl 228/4 29/203 B 29/628 tem for each head responds to signals from the digital 219/8 228/46 controller. Each control system automatically operates [51] Int CL B23k 1/00 the heads to lower the head into contact with a solder [58] Fieid 5 46 3 pad, to selectively apply heat to the pad to reflow solder the portion of the wire in contact with the pad, 29/203 203 576 219/85 and to raise the head to its normal position. The control system also operates electrical continuity checks [56] g ga f g gg to determine if each bond has been properly made and to continuously monitor for stripped insulation on the 2.637.096 5/]953 Luhn 29/33 wire cause short circuits After each bond 3 33 53? 3:82; 32 -g 5 4 1 is made, the wire is mechanically stressed to insure gu 18 e 3.192358 M965 Lasch, Jr et al 219/85 that the bond has the required mechanical strength. 3,307,763 3/1967 Rasimenoks et al 228/3 9 Claims, 72 Drawing Figures CONTROLLER t i I9 r 20 2| 22 l/ a wlL CONTROL EXTERNAL cgiimot coggao COtTROL FUNCTIONS I l 2 3 4 I i l l l L J L- A Law; .o

\ OPERA- lToR's PATENIEDBBT 81914 I 3.840.189

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1. Apparatus for automatically wiring circuit boards in a pointto-point wiring operation comprising: a plurality of solder heads in which heat is concentrated in the tip thereof and having an opening in said tip through which a supply of insulated wire extends, a table adapted for mounting circuit boards, one circuit board beneath each of said heads, said table and said heads being movable one with respect to the other so that said heads can be aligned with pads on said circuit boards to which said wire is to be soldered, a digital controller for positioning said table with respect to said heads to align said heads with a pad to which wire is to be soldered, said digital controller operating under control of a stored program, and a control system for each head, said control system being responsive to signals from said digital controller for automatically operating said head in operation of lowering said head into contact with a pad, selectively applying heat to the pad to reflow solder the portion of the wire in contact with the pad, and for raising said head.
 2. The apparatus recited in claim 1 wherein each of said control systems further comprises means for automatically initiating the flow of cooling air to the solder pad after the reflow soldering of the wire to the pad.
 3. The apparatus recited in claim 1 further comprising a probe and wherein each of said control systems further comprises: means for moving said probe into contact with the resulting bond, and means for checking electrical continuity between said wire and said probe to determine that an electrical connection has been made.
 4. The apparatus recited in claim 3 wherein each of said control systems further comprises means for initiating a new bonding cycle when a determination has been made that no electrical connection exists between said wire and said probe.
 5. The apparatus recited in claim 1 further comprising a wire gripper for each solder head and wherein each control system further comprises: means for activating said wire gripper after a bond has been made, said wire gripper applying mechanical stress to said bond to determine that a mechanically strong bond has been made.
 6. The apparatus recited in claim 1 wherein each of said control systems comprises: means operable when said head and said table are movable one with respect to the other for sensing electrical continuity between said wire and said head.
 7. Apparatus for automatically wiring circuit boards in a point-to-point wiring operation comprising: a bonding head having an opening through which a continuous supply of insulated wire extends, a table, said circuit board being mounted on said table, said table and said head being movable with respect to the other so that said head can be aligned with a point on said circuit board to which said wire is to be bonded, means producing relative movement between said head and said boaRd so that said head contacts the point on said board to which said wire is to be bonded, a probe, means for moving said probe into contact with the resulting bond, means for checking electrical continuity between said wire and said probe to determine that an electrical connection has been made, means operable when said head and said table are movable one with respect to the other for sensing electrical continuity between said wire and said tip, and an indicator actuated when said continuity exists to indicate that the insulation on said wire is stripped.
 8. The apparatus recited in claim 7 further comprising: a wire gripper, means for activating said wire gripper after a bond has been made, said wire gripper applying mechanical stress to said bond to determine that a mechanically strong bond has been made.
 9. Apparatus for automatically wiring circuit boards in a point-to-point wiring operation comprising: a plurality of solder heads in which heat is concentrated in the tip thereof and having an opening in said tip through which a supply of insulated wire extends, a table adapted for mounting circuit boards, one circuit board beneath each of said heads, said table and said heads being movable one with respect to the other so that said heads can be aligned with pads on said circuit boards to which said wire is to be soldered, a digital controller for positioning said table with respect to said heads to align said heads with a pad to which wire is to be soldered, said digital controller operating under control of a stored program, a control system for each head, said control system being responsive to signals from said digital controller for automatically operating said head in operation of lowering said head into contact with a pad, selectively applying heat to the pad to reflow solder the portion of the wire in contact with the pad, and for raising said head, a probe for each of said control systems, means for moving said probe into contact with the resulting bond, means for checking electrical continuity between said wire and said probe to determine that an electrical connection has been made, means in each said control systems for initiating a new bonding cycle when a determination has been made that no electrical connection exists between said wire and said probe, and means for supplying a lower heat to the solder tip during said new bonding cycle than in a normal bonding cycle whereby possible damage to the circuit board by application of too much heat is avoided. 